1. Field of the Invention
The present invention relates generally to the field of winding devices, and more particularly, to a ratchet mechanism for a retractor. Although the present invention is subject to a wide range of applications, it is especially suited for use as a small-card retraction device, and will be particularly described in that connection.
2. Description of the Related Art
A ratchet mechanism for a retractor prevents the retractor from retracting a cord into the housing of the retractor. Typically, ratchet mechanisms consist of a pawl which has a spring or gravity return and in the case of a mechanics rachet wrench the pawl can be "one direction" locking through a lever so that force can be applied in either a clockwise (CW) or counterclockwise (CCW) direction. Other similar devices, for example, spring-driven clock escapements, are intended to arrest a toothed gear from continuous movement to incremental rotation. All subject similar devices use a pawl which is fixed in the mechanism by a pivot pin. The pawl can be influenced in one direction by a spring or the force of gravity. The pawl is rendered inactive, or caused to be reversible, by a lever actuator.
In one example of a conventional retractor, U.S. Pat. No. 4,901,938 discloses an electrical cord retractor. A spiral spring biases a spool in the CW direction. A detent formed of a strip of springy metal is fixed at one of its ends to the inner surface of a base by a pin. Intermediate its ends, the detent presents a bulge adapted to engage indentations in a toothed wheel. When the bulge engages in one of the indentations, the detent prevents rotation of the spool under the influence of the spring.
An elongated actuator has one end located adjacent to the bulge and the other end extends through a hole in the base and carries a pushbutton. When the pushbutton is depressed, an end of the actuator pushes the bulge out of engagement with the indentations, thereby releasing the latching function of detent and wheel so as to free the spool for rotation by the spring. When the pushbutton is released, the resilience of the detent returns the actuator to its initial position and permits the bulge to engage one of the indentation to relatch the spool.
Although suitable for some applications, this retractor, however, does not allow the cord to be freely pulled out the ratchet wheel without actuating the lever and is an elaborate design requiring many parts that increases the cost of the retractor.
In another example of a conventional retractor, U.S. Pat. No. 5,509,616 discloses a retractable chalk line device. In particular, it discloses a thumb slide assembly for controlling the spool. The thumb slide assembly includes a thumb grip slidably mounted on a casing. A pair of opposed tabs project from the thumb grip and straddle the spool and engage associated teeth which are located on the opposing faces of the spool. When the grip is in a neutral position, the opposed tabs are disengaged from the spool teeth, allowing dispensing or retraction of the string. When the thumb grip is in a locked position, the opposed tabs are engaged with the spool teeth to restrict movement of the string.
Although suitable for some applications, this retractor, however, has the tabs in direct engagement with the teeth, which required the thumb assembly and teeth to be reinforced to handle the excessive wear and tear. Further, this retractor does not allow the cord to be freely pulled out without actuating the thumb assembly once it is in the locked position.
All of the above described devices require a number of expensive components, operate both above and to the side of the rotating member, take up an inordinate amount of space, and are typically reinforced to transmit torque from one rotating member to another.
A need therefore exists for a ratchet mechanism for a reel that provides the advantages of allowing the string to be freely pulled out the ratchet wheel without actuating the lever, simplifying the actuator design, and reducing the cost of the ratchet mechanism.